To generate a robust and effective immune response, T cells must integrate pathogen-derived and micro- environmental signals; these include availability of nutrients and oxygen. Together these signals regulate the metabolic changes necessary for the dramatic expansion of effector T cells armed to eliminate pathogens. We have found that a specific metabolic response pathway controls T cell immunity, and will identify the signaling and physiological parameters that link the metabolic activity of T cells during their response to pathogen with their differentiation and function. )